What could cause triggers to be hit for one user in DB, but not for another?

I have a large web application that relies on database (MSSSQL 2008) triggers to perform some of its functions. It offers a web-interface which allows the end user to make form-based changes to the database.

T开发者_JAVA技巧he issue is - when the web application is run with one userid in the apppool, the database triggers don't get triggered (they have logging functionality which enables me to see that); but if I change the userid in the AppPool to another username/password, these triggers are executed. Note that the table updates are performed in both scenarios. This is the only difference I can spot between the system behavior under the two different circumstances. Both users have dbo privileges, and are able to read/write into the database.

Any thoughts on what may be causing this?

Thanks.

*UPDATE: Neither user is sysadmin; this happens for ALL of my database triggers. *

*UPDATE #2: After digging more into the problem, I found out that the logging function was relying on a queue (yes, I know) that has inconsistent behavior for the two user accounts. To me this means that the permissions for both accounts are somehow mismatched and that is most likely the root of the problem. *

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This turned out to be a nondescript permissions error for that particular user account. When the account was removed from the database and added back in - the triggers, logging, and all related events started working appropriately.